1. In Data loader using upsert operation can u do update a record if that record id is already exist in page and if updated that record then can u update 2records with having same id and if not updated 2 records then wat error message is given?
It is not possible to update records with same id in a file usin upsert operation. It will throw “duplicate ids found” error.
2. One product cost is 1000. It is stored in invoice so once if change the cost of product to 800 then how can i update it automatically into a invoice?
We can achieve this using triggers or through relationship among objects.
3. One company is having some branches and all branches having different departments. So, now I want to display all departments from all branches in a single visualforce page?
Using subquery we can fetch all the required data and we can display it in VF page.